/*
 * Copyright (c) 1995-1999 Hannah Schroeter <hannah@mamba.pond.sub.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer,
 *     either in a separate file included with the distribution, or
 *     copied into the source files.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND HIS CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR HIS CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>

#include <sys/file.h>
#include <sys/param.h>
#include <sys/stat.h>

#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/* From .../sendmail/src/sysexits.h */
#define EX_OK 0
#define EX_USAGE 64
#define EX_OSERR 71
#define EX_CANTCREAT 73
#define EX_IOERR 74
#define EX_TEMPFAIL 75

#ifdef USE_FLOCK
#undef USE_FLOCK
#define USE_FLOCK 1
#undef USE_LOCKFILES
#else
#undef USE_LOCKFILES
#define USE_LOCKFILES 1
#endif

extern int errno;

#if USE_LOCKFILES
int lock (char *filename)
{
  int fd;
  fd = open (filename, O_CREAT | O_EXCL, 0000);
  if (fd >= 0) {
    close (fd);
    return 0;
  }
  if (errno != EEXIST) {
    perror("open (lockfile)");
    exit(EX_OSERR);
  }
  return -1;
}

void lockwait (char *filename)
{
  while (lock (filename)) sleep (2);
}

void unlock (char *filename)
{
  unlink (filename);
}
#endif /* #if USE_LOCKFILES */

void usage (char *av0)
{
  fprintf (stderr, "usage: %s -f from host user ...\n", av0);
  exit (EX_USAGE);
}

int main (int argc, char **argv)
{
  argv[0] = "bsmtp";
  argv[argc]=0;

  if (initgroups ("@DAEMONUSER@", @DAEMONGID@) < 0)
  {
    fprintf (stderr, "initgroups\n");
    exit (EX_OSERR);
  }

  if (setgid (@DAEMONGID@) < 0)
  {
    perror ("setgid");
    exit (EX_OSERR);
  }

  if (setuid (@DAEMONUID@) < 0)
  {
    perror ("setuid");
    exit (EX_OSERR);
  }

  if (argc < 5)
    usage (argv[0]);

  if (strcmp (argv[1], "-f"))
    usage (argv[0]);

  {
    char *from, *host;
#if USE_LOCKFILES
    char lockfilename [MAXHOSTNAMELEN+1+5];
#endif
    FILE *file;
#if USE_FLOCK
    int fd; /* for applying the advisory lock */
#endif
    size_t from_len;

    from = argv[2];
    /* remove redundant pairs of <> */
    from_len = strlen(from);
    while (from[0] == '<' && from[from_len - 1] == '>') {
      from[from_len - 1] = '\0';
      from++;
      from_len -= 2;
    }
    host = argv[3];
    argc -= 4;
    argv += 4;

    umask (0007);
    chdir ("@QUEUEDIR@");

#if USE_LOCKFILES
    sprintf (lockfilename, "%s.lock", host);
    lockwait (lockfilename);
#endif

    file = fopen (host, "a+"); /* + for locking */
    if (!file) {
      fprintf (stderr, "can't open file %s\n", host);
      exit (EX_CANTCREAT);
    }
#if USE_FLOCK
    fd = fileno (file);
   lockredo:
    if (flock(fd, LOCK_EX) < 0) {
      switch (errno) {
      case EBADF:
        fprintf (stderr, "Panic: flock returns EBADF\n");
        exit (EX_OSERR);
        /* NOTREACHED */
      case EINVAL:
        fprintf (stderr, "Panic: flock returns EINVAL\n");
        fprintf (stderr, "Was @QUEUEDIR@/%s not a plain file?\n", host);
        exit (EX_OSERR);
        /* NOTREACHED */
      case EINTR:
        goto lockredo;
      default:
	perror("Panic: flock");
	exit(EX_OSERR);
      }
    }
#endif
    fseek (file, 0, SEEK_END);
    fprintf (file, "MAIL FROM:<%s>\n", from);
    while (argc) {
      fprintf (file, "RCPT TO:<%s>\n", argv[0]);
      argv++; argc--;
    }
    fprintf (file, "DATA\n");
    { char buffer[1024]; size_t len;
      len = fread (buffer, 1, 1024, stdin);
      while (len > 0) {
        if (fwrite (buffer, 1, len, file) != len) {
          fprintf (stderr, "Can't write file %s\n", host);
          exit (EX_IOERR);
	  /* no unlock, so file can be repaired XXX */
        }
        len = fread (buffer, 1, 1024, stdin);
      }
      /* XXX check for errors, if len == 0 */
    }
    fprintf (file, ".\n");
    fclose (file);
#if USE_LOCKFILES
    unlock (lockfilename);
#endif
  }
  return (EX_OK);
}